The primary objectives of this study are to determine pharmacokinetic parameters of two preparations of genistein (i.e. a 43% genistein preparation and a 90% genistein preparation) in humans and to determine toxicity of each preparation when administered as a single dose. The secondary objectives are to determine effects of a single dose of genistein on phosphotyrosine levels in peripheral mononuclear cells and to determine relative bio-availability of two preparations of genistein in humans.